The present invention relates to a ball mill for pulverizing various materials such as ferrite, metal powder, minerals, foods and the like to finer particles, the material to be pulverized being placed in a container together with pulverizing balls and agitating forces being applied to the material and the balls. More particularly, the invention relates to an improvement in a ball mill comprising a container for receiving a material to be pulverized and pulverizing balls, and an agitator including arms rotatable on a vertical axis and carrying elongate agitating means extending along and revolvable about the vertical axis.
A known ball mill of this type is disclosed, for example, in Japanese Patent Publication No. 45-22280. This prior art ball mill will be described first with reference to FIG. 7 of the accompanying drawings. The ball mill comprises a container 25 housing a vertical rotary shaft 26. The rotary shaft 26 carries a plurality of arms 27 all disposed in a space filled with a material to be pulverized and the balls. Each of the arms 27 carries an agitating member 28 standing upright thereon.
In the known construction, not only the agitating members for imparting agitating forces but also the arms for supporting the agitating members are disposed in the space filled with the material and balls to revolve with the agitating members. This construction, therefore, has the disadvantages that the speed of pulverization is slow for the power consumption and that the balls become worn quickly.